Fix markup in javadoc.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1611966 13f79535-47bb-0310-9956-ffa450edef68
Add Runnable wrapper method for use with Async Servlets.

  - Updated documentation.
  - Moved implementation of getLog4jWebInitializer into WebLoggerContextUtils.
  - Added WebLoggerContextUtils which is similar to Spring's WebApplicationContextUtils class.
  - Added test servlet for later integration testing (also used for example documentation).

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1611967 13f79535-47bb-0310-9956-ffa450edef68
Add @since 2.0.1 to new methods.

git-svn-id: https://svn.apache.org/repos/asf/logging/log4j/log4j2/trunk@1611968 13f79535-47bb-0310-9956-ffa450edef68